2MASS J05352184−0546085
Eclipsing binary brown dwarf in the Orion Nebula
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2MASS J05352184-0546085, abbreviated to 2M0535-05 and also known by its variable star designation V2384 Orionis, is a young eclipsing binary brown dwarf system in the Orion Nebula, about 1,200 light-years (370 parsecs) away. It was discovered in 2006 and was the first eclipsing brown dwarf system to be discovered,[5][6] predating the discovery of the transiting brown dwarf CoRoT-3b in 2008.
 Artist's impression of the 2M0535-05 system | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 21.84732s[1] |
| Declination | −05° 46′ 08.5714″[1] |
| Characteristics | |
| Evolutionary stage | brown dwarf |
| Spectral type | M6.5±0.5[2] |
| Apparent magnitude (J) | 14.65±0.03[3] |
| Apparent magnitude (H) | 13.90±0.04[3] |
| Apparent magnitude (K) | 13.47±0.03[3] |
| Variable type | eclipsing binary |
| Astrometry | |
| Proper motion (μ) | RA: 1.960 mas/yr[1] Dec.: −0.049 mas/yr[1] |
| Parallax (π) | 2.6730±0.2658 mas[1] |
| Distance | 1,200 ± 100 ly (370 ± 40 pc) |
| Orbit[4] | |
| Period (P) | 9.779556(19) d |
| Semi-major axis (a) | 0.0407±0.0008 AU |
| Eccentricity (e) | 0.3216±0.0019 |
| Inclination (i) | 88.49±0.06° |
| Argument of periastron (ω) (secondary) | 215.3±0.5° |
| Semi-amplitude (K1) (primary) | 18.61±0.55 km/s |
| Semi-amplitude (K2) (secondary) | 29.14±1.40 km/s |
| Details[4] | |
| A | |
| Mass | 0.0572±0.0033 M☉ |
| Radius | 0.690±0.011 R☉ |
| Surface gravity (log g) | 3.52±0.03 cgs |
| Temperature | 2715±200 K |
| Rotation | 3.293±0.001 d |
| Rotational velocity (v sin i) | 10[2] km/s |
| Age | ~1 Myr |
| B | |
| Mass | 0.0366±0.0022 M☉ |
| Radius | 0.540±0.009 R☉ |
| Surface gravity (log g) | 3.54±0.03 cgs |
| Temperature | ~2850[a] K |
| Rotation | 14.05±0.05 d |
| Rotational velocity (v sin i) | <5[2] km/s |
| Age | ~1 Myr |
| Other designations | |
| V2384 Ori, 2MASS J05352184-0546085[3] | |
| Database references | |
| SIMBAD | data |
The pair orbit each other with a period of 9.8 days, and are about 60 and 38 times the mass of Jupiter, respectively. The system is very young, at an age of about 1 million years, so the brown dwarfs have yet to cool; they are M-type objects with temperatures comparable to red dwarf stars, and they are inflated in size to over half the radius of the Sun.[4][6] The primary is observed to rotate with a period of 3.3 days and the secondary 14 days, indicating that they have not yet become tidally locked to each other.[4]
Unexpectedly, the less massive (secondary) brown dwarf is the hotter of the pair.[6][2] Possible explanations for this temperature reversal include the two brown dwarfs differing slightly in age;[2] strong magnetic fields on the primary inhibiting convection,[2] supported by the primary's observed fast rotation and strong hydrogen-alpha emission;[7] large starspots on the primary,[4] though this was found to be unsupported by evidence;[8] and tidal heating, which is unlikely to be solely responsible for the temperature reversal.[9]
No infrared excess that would indicate the presence of a circumstellar disk has been detected in this system.[10] The system is a source of X-ray emission.[11]
See also
- 2M1510, another eclipsing binary brown dwarf
Notes
- Derived from the primary temperature of 2715 K and the secondary/primary temperature ratio of 1.050